Telephone-exchange system.



A. E. LUNDELL. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE 13, I916.

Patented Jan.29,191&

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TELEPHONE EXCHANGE SYSTEM.

APPLICATION men JUNE 13. ms.

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TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE I3. 1916.

Patented Jan. 29, 1918.

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Ava/am 10/4 A/laem Lynda/A .MLBEN E. LUNDELL, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

To all whom it may concern:

Be it known that T, ALBEN E. LUNDELL, a citizen of the United States, residing at New York, in the county of. Bronx and State of New York, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description.

change systems, and more particularly to line testing and guarding. arrangements for automatic or semi-automatic telephone exchanges.

lln telephone exchanges, outgoing lines, such as trunk lines, must be guarded against seizure by interconnecting means, such as selector switches, while the lines are used by another selector switch and until the line is actually again out of use. In order to guard a line seized by a selector, it has been common to provide a test circuit including a test contact of the selector, and in order to guard the line while the switch at the other end is being returned to normal, a make-busy circuit may be established for the trunk. Hitherto this make-busy circuit has not been closed until a relay controlling the holding of the trunk, 71. e., the test circuit, is completely deenergized or energlzed, and consequently there has been an interval equal to the length of time required by the relay to release, or to energize, during which the trunk line does not test busy. During this interval another trunk hunting selector may pass over a multiple test terminal of the trunk, and, finding that the terminals test idle, will seize the trunk and closea controlling circuit for a connecting means, such as a selectively operable connector switch, to which this trunk line leads. If this last mentioned switch is in an ofl-normal position, it may be caused to select the wrong line.

It is the object of this invention to remedy such unreliable testing arrangements by providing a trunk holding means in a system of the above type, for guarding the trunk until the switches in the stationary and movable contacts of which the trunk line terminates, are actually released to normal.

In the drawings, Figure 1 represents a calling subscribers line, an operators connecting circuit and a selector switch; Fig. 2

This invention relates to telephone ex-- Specification of Lettert Patent. Patna-mated Jam, 29, 1]]911 Application filed June 13, 1916. Serial No. 103,388.

(to be placed to the right of Fig. 1) a connec tor switch adapted to seize a called subscribers line; and Fig. 3 (to be placed below Fig. 1) an operators controlling apparatus by means of which the selector and connector switches may be set.

The selector and sequence switches and the controlling apparatus therefor will not be disclosed in full in the following description of this system, switches of this type being well-known in the art. A complete description of such switches maybe had from a patent No. 1,168,319, patented January 8, 1916, to A. E. Lundell.

The calling subscriber at station 100, desiring to obtain a connection with a subscriber at station 200, removes his receiver from the switchhook, closing thus a. circuit for line relay LR, which lights a calling signal CL. The operator, noticing lamp CL lighted, inserts a plug 101 into a jack 102 in which the calling line terminates, whereupon a circuit is closed from grounded battery through the winding of cut-off relay CR, the sleeve contacts of jack 102 and plug 101, and the winding of a relay 103 to ground. Relay 103 closes a circuit from ground through its armature and front contact, a contact 104 and the power magnet of a sequence switch 105 to grounded battery. Under the control of a normal spring 106, sequence switch 105 is moved out of position 1 into position 2. A circuit is now closed from ground through sequence switch contact 107, conductor'108, a contact 300 of a sequence switch 301, and the winding of a relay 302 to grounded battery. Relay 302 becomes energized and closes a circuit from ground through its left-hand armature and front contact, a contact 303 and the power magnet of the sequence switch 301 to grounded battery. Under the control of a normal spring 301, sequence switch 301 is moved out of position 1 into position 3. Relay 302 does not become deenergized when sequence switch 301 leaves position 1, a circuit being closed from grounded battery through the winding of this relay, sequence switch contact 305, the right-hand armature and front contact of relay 302, conductor 306 and contact 109 of sequence switch 105, to ground.

The operator, by depressing her listening key 110, connects her telephone set 111 into telephonic association with the calling subits scriber, and, in accordance with instructions received from the subscriber, she adjusts her controlling apparatus. Only tworows of keys are shown in Fig. 3, as it is thought suflicient for the purpose of the present invention to describe the setting of an inter connecting means such as a selector switch 112 and a connecting means such as a selectively operable connector switch 201, re-

spectively, in accordance with one digit of the called subscribers number. It will be obvious to those skilled in the art that both switches will be set in accordance with a plurality of digits in order to extend the callin line toward the called line and that for this purpose a plurality of rows of keys must be provided at the operators position. Supposing, however, that the called. subscribers line may be seized by causing selector switch 112 and connector switch 201 to take ten steps, respectively, the operator will depress keys 310 and 311 and a startkey 312. A circuit is established from groundthrough the contact of key 312, a contact 313, and the power magnet of sequence switch 301 to grounded battery, for

moving this sequence switch into position 4.

A circuit is then closed from grounded battery through the winding of relay 113, sequence switch contact 114, conductor 115, sequence switch contact 314, the outer armature and back contact of the upper counting relay 0, the winding of a stepping relay 315, conductor 316, and a sequence switch contact 116 to ground. Relays 113 and 315 become energized. Relay 113 closes a circuit from ground through its right-hand armature and front contact, a sequence switch contact 117, conductor 118, and the power magnet of the sequence switch 105 to grounded battery, for moving this sequence switch into position 3. Relay 113 remains energized upon the opening of contact 114, due to the closure of a substitute path through the left-hand armature and front contact of this relay; and a sequence switch contact 119.

Upon the energization of relay 315, a circuit is closed from ground through the front contact and armature of this relay, a sequence switch contact 317, conductor 318,

the contact of the key 310, conductor 322,

the armature and back contact of the uppercounting relay 9 and the windin of the lower counting relay 9 to grounde battery. The lower counting relay 9 closes a circuit from ground through sequence switch contact 320, conductor 321, the armature and front contact of the lower counting relay 9,

. counting relays 9 to grounded battery. Theand the windings-of the upper and lower upper counting relay 9, however, cannot become energized due to the closure of a short circuit around its winding from ground through sequence switch contact 330, to

120, a sequence switch contact 121, and the right-hand front contact and armature of relay 113 to ground. Magnet 120 attracts its armature 122 and presses thus a brush rod 123 against a roller 124 constantly rotating in the direction indicated by the arrow. The brush rod with selector wipers 124, 125, 126 and commutator brushes 127, 128 is moved in an upward direction, the wipers 124, 125, 126 wiping over a terminal bank 129 and the commutator brushes 127, 128 'over conductingand insulated segments of a commutator plate 130. When the commutator brush 128 engages a conducting segment 131, it connects ground through this segment, a conductor 132, sequence switch contact 133 and 119 to relay 113, thus shunting out relay 315. Relay 315 opens at its front contact the short circuit of the upper counting relay 9, whereupon this counting relay becomes energized and connects conductor 322, through its armature and front contact, the armature and back contact of the upper counting relay 8, the winding of the lower counting relay 8, and conductor 323, to grounded battery. The lower counting relay 8 connects now the upper-counting relay 8 into circuit. This relay, however, cannot become energized due to the fact that commutator brush 128 moved in the meantime into engagement with an insulated segment 134, permitting thus the reenergization of relay 315, which again connects ground to conductor 322.

The operation of the counting relays continues in substantially the same manner until the selector 112 has been moved upward by ten 'steps and the upper counting relay 0 became energized. This counting relay opens, at its outer armature, the fundamental circuit including relays 315 and 113, and closes a circuit from ground through sequence switch contact 324, the inner armature and front contact of the upper counting relay 0 and the power magnet of sequence switch 301 to grounded battery, for moving this sequence switch into position 6. When the sequence switch leaves position 4, all the counting relays which have been locked up become deiinergized. Relay 113, upon deenergization, closes a circuit from ground, through its right-hand armature and back contact, sequence switch contact 135, conductor 118, and the power magnet of sequence switch 105 to grounded battery, for moving this sequence switch into position 6. When sequence switch 105 leaves osition 3, the magnet 120 becomes deenergized. A circuit is now closed from ground through sequence switch contacts 136 and 137, and the righthand winding of a relay 138, to grounded position 1 and thus a battery. Let us suppose, that the trunk line 202, 203, 204 termmating'in the tenth row of contactsof terminal bank 139 is idle, that is to say,.no busy ground potential is connected to a test contact 139 and the multiples thereof. 'When this trunk is idle, sequence switch 205 associated with selector 201. is in trunk holding relay 206 is deenergized.

The relay 138 closes a circuit from.

contact, a sequence switch contact 140, con- .ductor- 118, and the power magnet/of sequence switch 105, to grounded battery, whereupon the sequence switch will be moved into position 7. When the sequence switch 105 leaves position 6, the circuit of relay 138 is opened at contact 136. As will be hereinafter'described, if trunk 202, 203, 204

is busy, the relay 138 will be maintained energized in positions 6 and 7 of the sequence switch for causing the movement of selector 11.2 onto the terminals of another trunk.

quence switch 205 in position 1, and all of the counting relays are deenergized.

The fundamental circuit therefore, will be again closed, but now from grounded battery, through the winding of the relay 207,

sequence switch contact 208, trunk conduc tor 202, wiper 124 of selector 112, sequence switch contact 150, conductor 115, sequence switch contact 314, the outer armature and back contact of the upper counting relay 0, the winding of stepping relay 315, conductor 316, sequence switch contact 151, wiper 125 of selector 112, trunk conductor 203, and

sequence switch contact 209 to ground. Relay 207 closes a circuit from ground through its right-hand armature and front contact,

- a contact 210, and the power magnet of sequence switch 205 togrounded battery for moving this sequence switch into position 2. The relay 207, in the same manner as relay 113 locked up, locks up through its left-hand front contact and armature and sequence switch contact 211, and thus will not become denergized when sequence switch 205 leaves position 1.

Tn position 2 of sequence switch 205, a circuit is closed from ground through sequence switch contact 212, the left-hand and the non-inductively wound middle windings of relay 206 to grounded battery. This relay ound through its right-hand armature an front comes now energized, a circuit being closed closes a circuit from round through its right-hand armature and tact 213 and the power magnet of sequence front contact, conswitch 205 to grounded battery, whereupon this switch is moved into position 3. In

this position of the sequence switch, the

r ght-hand winding of relay 206, which is differentially wound with, respect to the other wmdingsof this relay, is shunted by a circuit extending over 204, 139, 126, 152,

153 to ground.v

A driving magnet 215' of connector 201 befrom grounded battery through the winding of this magnet, a sequence switch contact 216, and the right-hand front contact and armature of relay'207 to ground. Magnet 215, by attracting its armature 217, presses a brush rod 218 against a roller 219 constantly rotating in the direction indicated by the arrow, and the connector wipers 220, 221,. 222 and commutator brush 223 are caused to move in an upward direction. The wipers 220, 221 in which trunk line 202, 203 terminates and test wiper 222 are adapted to wipe over a contact bank 224 in which called lines terminate, and brush 223 over conducting and insulated segments 225 and 226 of a commutator plate 227.

Relay 315, upon energization, closes a circuit from ground through its front contact and armature, sequence switch contact 330, conductor 331, and the contact of key 311, conductor 332, armature and back contact of upper counting relay 9 and the winding of the lower counting relay 9 to grounde battery. The counting relays operate in the same manner as above described under the control of stepping relay 315.

The short circuits for the stepping relay are closed from ground through commutator brush 223, conducting segment 225, conductor 230, sequence switch-contacts 231 and 211 to relay 207. Upon energization, the upper counting relay 0 opens the fundamental circuit at its outer armature, whereupon relays 315 and 207 become denergized. The upper counting relay 0 closes also a circuit from ground through sequence switch contact 324, its inner armature and front contact, and the power magnet of sequence switch 301 to grounded battery, for moving this sequence switch out of position 6 into position 16, whereupon a circuit is closed from ground through sequence switch contact 335, conductor 336, a contact 155 and the power magnet of se quence switch 105 to grounded battery, and

this sequence switch is moved out of position 11 into position 16. Upon the opemng of contact 109 of sequence switch 105, relay' 302 becomes deenergized and closes a circuit from ground through its left-hand armature and back contact, a contact 337 and the power magnet of sequence switch 301 to grounded battery, for moymg th s sequence switch out of position 16 into posltion 1.

Upon the deenergization of relay 207, a circuit is closed from ground through the right-hand armature and back contact of this relay, contact 232 andthe power magnet of sequence switch 205 to grounded battery, for moving this sequence switch out of position 3 into position 13. The driving magnet 215 becomes deenerglzed and the connector wipers are stopped in engagement with the terminals of the called line. After the testing of this line in the well-known manner through a contact 233 of sequence switch 205, a ringing circuit is closed from a ringing current source 234 through the winding of'relay 235, sequence switch contact 236, wiper 221, the called substation circuit, wiper 220, and sequence switch contact 237, to ground. Upon the removal of the receiver at the called substation, the marginal relay 235 becomes energized and closes a circuit from ground through sequence switch contact 238, the front contact and armature of relay 235 and the power magnet of sequence switch 205 to grounded battery, for moving this sequence switch out of position 13 into position 16. When sequence switch 205 leaves position 13, relay 235 becomes deenergized.

The calling and called subscribers are now connected in a telephonic circuit indicated in heavy lines in the drawings.

The subscribers desiring disconnection restore their receivers to the switchhooks, causing thus, in the well-known manner, the actuation of supervisory signals 160 and 161, respectively. The operator noticing the actuation of these signals removes plug from jack 102, whereupon relays CR and 103 become deenergized, the latter closing a circuit from ground through its armature and back contact, and a contact 162 and the power magnet. of sequence switch 105 to grounded battery, whereupon this sequence switch is moved into position 18. In position 18 of the sequence switch, a circuit is closed from grounded battery, through the winding of magnet 163 and a sequence switch contact 164 to ound. Magnet 163 presses, by means 0 its armature 165, the brush rod 123 against a roller 166 constantly rotating in the direction indicated by the arrow, and the brush rod with the wipers and brushes mounted thereon is moved in a downward direction. When the brush rod reaches its normal position, a circuit is closed from of position 18 into position 1. When the sequence switch leaves position 18, magnet 163 becomes deenergized.

When sequence switch 105 leaves position 16%, contact 153 is opened and the short circuit is removed from the difi'erential right-hand winding of relay 206. This windingds now included in' a circuit from ground through sequence switch contact 240, the right-hand winding of relay 206, the left-hand armature and front contact and the left-hand and middle windings of relay 206 to grounded battery, and relay 206 becomes deenergized. If, during the restoration of selector 112, another selector 112 is moved to a multiple of the terminals of trunks 202, 203, 204, the relay 138 of such selector will remainenergized in position 7 of the sequence switch 105 associated with such selector, because a circuit exists from grounded battery through the left-hand winding, front contact and inner armature of such relay 138, conductor 152, the wiper 126 of that selector, conductor 204, the righthand winding of relay 206 and sequence switch contact 240, to ground. Relay 138 of such selector closes a circuit from ground through its right-hand armature and front contact, sequence switch contact 145 and the magnet 120 to grounded battery, and the selector switch will thus be moved on to the next set of trunk terminals.

The relay 206 being released, its righthand armature closes a circuit from ground through contact 241 and the power magnet of sequence switch 205 to grounded battery for moving this sequence switch into position 18. In this position of the sequence switch, a circuit is closed from. ground through sequence switch contact 242 and the winding of a magnet 243 to grounded battery. Under the control of magnet 243, the connector 201 is restored to its normal position. When brush 223 engages its normal segment 244, a circuit is closed from ground through brush 223, conducting segment 244, conductor 245, and a contact 246 and the power magnet of sequence switch 205 to grounded battery, for moving this switch into position 1. In position 1 of sequence switch 205, the trunk 202, 203, 204 may be again seized in the above described manner.

It will be seen from the above that the trunk 202, 203, 204 is guarded upon its seizure by selector 112 due to the connection of a ground potential through sequence switch contact 153. After selector 112 has been released and until the connector returns to normal, the trunk line is guarded by the ground potential applied through sequence ltl lit

switch contact M0 and the right-hand winding of relay 206 to the test. conductor 204:, t. e., irrespective of the energized or denergized condition of relay 206.

What 'isclaimed is:

1. In a telephone exchange system, a plurality of incoming lines, a trunk line, connecting means in which said trunk line terminates, a plurality of interconnecting means by which said incoming lines may be extended to said trunk line, testing means associated with the connecting means, restoring means for said interconnecting and connecting means, means for operating the restoring means of said connecting means in response to the restoration of said interconnecting; means, and means for preventing the extension of an incoming line to said trunk line while any one ofsaid interconnecting or said connecting means is actuated.

2. In a telephone exchange system,a plurality of incoming lines, a trunk line, selector switches in which said incoming lines terminate, a selectively operable switching device in which said trunk line terminates controlling apparatus tor operating any oi said selector switches to seize said trunk line, said switching device being operable by said controlling apparatus, testing means associated with each of the selector switches, restoring means for said selector switches and said switching device, means operable in response to the restoration of a selector switch for operating the restoring means of said switching device, and means for preventing the seizure of the busy trunk line while any of said selector switches or said selectively operable device are operated.

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3. In a telephone exchange system, a plurality of incoming lines, an outgoing line, connecting means in which said outgoing line terminates, a plurality of interconnecting means for extending said incoming lines to the outgoing line, means for operating said interconnectingand connecting means, a test contact for each of said interconnecting means, a relay for said outgoing line, means for connecting a busy potential to said test contacts upon the actuation of any of said interconnecting means, and means for connecting a busy potential to said test contacts through a winding of said relay upon the actuation of said connecting means.

4. In a telephone exchange system, a plus rality of incoming lines, an out oing line, connecting means in which sai outgoing line terminates, a plurality out" interconnecting means for extending said incoming lines to the outgoing line, a test contact for each of said interconnectin means, a difierentially wound relay or said connecting means, means for operating said interconmeeting and connecting means, means operative upon the actuation of one of said interconnecting means for connecting a busy potentialto said test contacts through a contact of said relay, and means operative upon the actuation of said connecting means for connectin the busy potential to said test contacts t rough a winding of said relay.

5. In a telephone exchange system, a plu-- rality of incoming lines, an outgoing line, a plurality of inte connecting means for extending said incoming lines to said outgoing l1ne, a test contact for each of said interconnectmg means, a relay for said connecting means, means for connecting a busy potential to sa1d test contacts through a contact of sand relay, and means for connecting the busy potential to said test contacts-through the winding of said relay.

6 In a telephone exchange system, a plurallty pf incoming lines, an outgoing line, a plurality of interconnecting means for assoclating sald mcoming lines with said outgong line, test contacts for said interconnecting means, a relay for said connecting means, means operative upon the actuation of said relay for connecting a busy potential to said test contacts, and means for connecting the busy potential to said test contacts irrespectlve of the electrical condition of said relay.

7 ][n a telephone exchange system, a plurality pf incoming lines, an outgoing line, a plurality of interconnecting means for extending said incoming lines to said outgoing line, test contacts for said interconnecting means, a difierentially wound relay for said connecting means, means operative in response to the actuation of said connecting means for connecting a busy potential to said test contacts, and means for connecting a busy potential to said contacts through a winding of said relay.

8. In a telephone exchange system, a plultltl lllt rality of incoming lines, a connecting'means,

an outgoing line terminating therein, a plurallty of interconnecting means by which said incoming lines may be extended to said outgolng line, test contacts for said interconnectlng means, a relay having two windings and a difi'erential winding, a circuit closed upon the seizure of the outgoing line by any of said interconnecting means for the two wlndmgs of said relay, means operative upon the actuation of said connecting means for short-circuiting the difi'erential winding of said relay, and means for applying a busy potential to said test contacts upon the actuationot said connecting means through the. difl'erential winding of said relay.

9;. In a telephone exchange system, a plurallty of incoming lines, a connecting means, an outgoing line terminating therein, a plurality of interconnecting means by which said incoming lines may be extended to said outgoing line, test contacts for said interconnecting means, a relay having two windings and a third difi'erential winding, a releasing means tor each ct said interconnec llltll means, and a releasing means for said conthe release of said interconnectmg means for energizing said third difi'erential winding of the relay, means for connecting a busy potential to said test contacts upon the seizure of said outgoing line'by any of said interconnecting means, and means for connecting a busy potential to saidxtest contacts through the differential winding of said relay upon the actuation and during the release of said connecting means.

- 10. In a telephone exchan e system, a plurality of incoming lines, a se ector switch for each of said incomin lines, a connector switch, a trunk line lea ing thereto, controlling apparatus for causing any one of said selector switches to seize said trunk line and for setting said connector switch, a test contact for each of said selector switches, a relay associated with said connector switch having two windings, a circuit closed through said relay windings upon the seizure of said trunk line by any one of said selectors, means for connecting a busy potential to said test contacts, a third, differential winding for said relay, means for short-circuitin sald winding while the selector switches and a connector switch are set, releasin means for said connector controlled by said relay and a releasing means for each of said selector switches, means for energizing the third winding of said relay upon the release of said selector switch, and means for connecting the busy potential to the test contacts through said third winding of the relay during the setting and the release ofsaid connector switch.

In witness whereof, I hereunto subscribe my name this 12th day of June A. D., 1916.

ALBEN E. LUNDELL. 

